Hi Neeraj,
I can’t answer your question regarding search. If you need more details here I would recommend to open a support case with Microsoft.
About PSConfig: This IS required even if no db Sheena changes are in the fix. See here for details:
https://blogs.technet.microsoft.com/stefan_gossner/2015/09/09/why-we-recommend-require-to-run-the-configuration-wizard-also-for-security-fixes/
Cheers,
Stefan